•LVO/PEDOT composites are successfully prepared via in-situ chemical oxidative polymerization method.•20 wt% LVO/PEDOT composite demonstrates the excellent rate capability and cycling stability.•EIS test shows that decreased Rct and increased DLi+ are exhibited for 20 wt% LVO/PEDOT composite.•Ex-situ XRD analysis proves the good structural stability of 20 wt% LVO/PEDOT composite.•The introduction of PEDOT effectively buffers the volume changes of LVO electrode upon cycling.LiV3O8/poly (3, 4-ethylenedioxythiophene) (LVO/PEDOT) composites were synthesized via an in-situ oxidative polymerization process. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, galvanostatic discharge/charge tests, and electrochemical impedance spectroscopy techniques are used to characterize the as-prepared samples. The results demonstrated that the electrochemical performances of LVO/PEDOT composites have greatly improved in comparison with bare LVO. The discharge capacities of 20 wt% LVO/PEDOT composite are 270, 265, 252, 240, and 229 mAh g− 1 and ˃95% capacity retention is maintained after the charge-discharge 50 cycles at the current densities of 60, 90, 120, 180, and 240 mA g− 1, respectively. A high reversible capacity of 176 mAh g− 1 (only 58 mAh g− 1 for the bare LVO) can be maintained after 50 cycles at a very high current rate of 2000 mA g− 1. Electrochemical impedance spectra results implied that the 20 wt% LVO/PEDOT composite revealed a decreased charge transfer resistance and increased Li+ ions diffusion ability. This noteworthy improvement is ascribed to the combination of PEDOT, which can act just as a defending layer to inhibit the LVO from direct contact with electrolyte and buffer volume change, and act just as a conductive network to improve the electronic conductivity, thus cycling stability and rate capability are improved.Download high-res image (266KB)Download full-size image

•LVO/PDAQ composite was prepared by in situ chemical oxidative polymerization method.•LVO/PDAQ composite exhibited the high cycling stability and rate capability.•Decreased Rct and high DLi+ were shown for LVO/PDAQ composite.•LVO/PDAQ composite can be used as a good cathode in rechargeable lithium batteries.LiV3O8/10 wt% poly(1,5-diaminoanthraquinone) composite was prepared by a in situ chemical oxidative polymerization process and applied as cathode material for rechargeable lithium batteries. Due to the introduction of poly(1,5-diaminoanthraquinone) and electrochemical synergistic effect, the composite demonstrated better rate capabilities and cycling performances compared to the bare LiV3O8 sample.

Hollow-sphere ZnSe is successfully obtained through Ostwald ripening. Carbon nanoparticles are designed and utilized to form a wrapped carbon network as a conductive buffering matrix by subsequent annealing. The ZnSe/C composites, as anode materials for lithium-ion batteries (LIBs), exhibit excellent Li+ storage properties, delivering a high reversible capacity of 573.7 mA h g−1 at 1.0 A g−1 after 800 cycles. Even upon increasing the high current density to 20.0 A g−1, the reversible capacity can achieve 318.8 mA h g−1 after 5000 cycles. The superior rate capability is confirmed through the current density return from 20.0 to 1.0 A g−1, and ZnSe/C composites still recover up to 469 mA h g−1, with a retention of 92%. The enhanced electrochemical performances of ZnSe/C composites are attributed to the unique structure and the introduction of conductive carbon networks, which can improve the Li+ diffusion coefficient in the insertion and extraction process. Furthermore, the interconnected network also alleviates the volume variation during cycling and further enhances the structural stability.

In this work, a highly sensitive hydrogen peroxide (H2O2) biosensor based on immobilization of hemoglobin (Hb) at Au nanoparticles (AuNPs)/flower-like zinc oxide/graphene (AuNPs/ZnO/Gr) composite modified glassy carbon electrode (GCE) was constructed, where ZnO and Au nanoparticles were modified through layer-by-layer onto Gr/GCE. Flower-like ZnO nanoparticles could be easily prepared by adding ethanol to the precursor solution having higher concentration of hydroxide ions. The Hb/AuNPs/ZnO/Gr composite film showed a pair of well-defined, quasi-reversible redox peaks with a formal potential (E0) of −0.367 V, characteristic features of heme redox couple of Hb. The electron transfer rate constant (ks) of immobilized Hb was 1.3 s−1. The developed biosensor showed a very fast response (<2 s) toward H2O2 with good sensitivity, wide linear range, and low detection limit of 0.8 μM. The fabricated biosensor showed interesting features, including high selectivity, acceptable stability, good reproducibility, and repeatability along with excellent conductivity, facile electron mobility of Gr, and good biocompatibility of ZnO and AuNPs. The fabrication method of this biosensor was simple and effective for determination of H2O2 in real samples with quick response, good sensitivity, high selectivity, and acceptable recovery.Graphical abstractHighlights► Graphene, flower-like zinc oxide, and gold nanoparticles integrated composite electrode was prepared. ► Hemoglobin immobilized at the modified electrode for hydrogen peroxide sensing. ► Good sensitivity, wide linear range, and low detection limit were obtained. ► The developed biosensor showed a very fast response (<2 s) toward H2O2.

A novel electrogenerated chemiluminescence (ECL) assay for sensitive determination of thrombin is designed employing CdSe/ZnS quantum dots served as an ECL label. This ECL sensor is fabricated on graphene modified glassy carbon electrode which is then covered with a low surface coverage of gold nanoparticles (AuNPs). An aptamer is used to selectively recognize the target. The thiol-terminated aptamer is first immobilized on AuNPs/graphene modified electrode, and then thrombin is imported to form the aptamer–thrombin complexes. After blocking the nonspecifically bound oligonucleotides with MCH solution, another CdSe/ZnS quantum dots modified aptamer is hybridized with the free thiol-terminated aptamer to form a DNA complexe. A decreased ECL signal is observed upon recognition of the target thrombin. The integrated ECL intensity versus the concentration of thrombin is linear in the range from 0.01 to 50 nM. The detection limit is 10 fM. The present aptasensor also exhibits excellent selectivity, stability and reusability. This sensing system can provide a promising label-free model for aptamer-based compounds sensitive detection.Graphical abstractHighlights► A electrogenerated chemiluminescence assay for thrombin is designed. ► CdSe/ZnS quantum dots are served as ECL label. ► Low surface coverage of gold nanoparticles is involved to improved sensitivity. ► The sensing system is based on the utilization of aptamer as the probes.

A LiV3O8/polyaniline (PAn) composite was prepared by the in-situ polymerization method assisted by sodium dodecyl sulfate and ammonium persulfate. The as-prepared powders were investigated by XRD, SEM, and galvanostatic discharge/charge analysis. It was found that the introduction of PAn to LiV3O8 can effectively buffer the mechanical stress and restrain the number of phase changes of composite material during the electrochemical cycling. Compared with pristine LiV3O8, LiV3O8/PAn composite maintains a reversible capacity of 212.1 mAh g−1 at the current density of 30 mA g−1 after 50 cycles, approximately 22.6%, much higher than the former.

Co3(PO4)2-coated LiV3O8 has been successfully synthesized and used as positive material for rechargeable lithium batteries by a facile liquid phase method. The as-prepared powders were characterized by x-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and the galvanostatic discharge/charge experiments. As-prepared Co3(PO4)2-coated LiV3O8 forms a good layered structure with a poor cyrstallinity. SEM reveals that Co3(PO4)2-coated LiV3O8 has uniform particle distribution and reduced particle size when compared with bare one. The Co3(PO4)2 coating layer is about 33–59 nm forming a continuous lumps attached to LiV3O8 particle surface. Co3(PO4)2-coated LiV3O8 electrode shows increased capacity and more stable cycling. The first and 35th discharge capacities of the Co3(PO4)2-coated LiV3O8 electrode are 322.8 mAh g−1 and 235.7 mAh g−1 in the range of 4.0–1.8 V at a current rate of 30 mA g−1, respectively. The improved electrochemical performance is assigned to the greatly reduced LiV3O8 particle with uniform morphology. Co3(PO4)2-coating further benefits the phase transitions of LiV3O8 during discharge/ charge while preventing parasite reactions between electrode surface and electrolyte.

Polycrystalline LiNi0.8Co0.2O2 powders were synthesized via the citric acid-assisted liquid phase evaporation method. The precursors are homogenously mixed in the solutions at an atomic scale which is also reflected by the particle distribution of the final products. The optimal synthesis temperature is located at 750 °C where the particle size, crystalline structure, and the cation disorder between Li+ and Ni2+ ions have been balanced. A high discharge capacity of 191 mAh g–1 (3.0–4.3 V at 30 mA/g) is achieved in the first cycle for the 750 °C-prepared sample with a capacity retention of 89.37% after 96 cycles. Cyclic voltammetry and the differential capacity curves also reveal a moderate stable crystal structure of 750 °C-prepared LiNi0.8Co0.2O2 during the prolonged cycles.

Li1.2V3O8 and Cu-doped Li1.2V3O8 were prepared at a temperature as low as 300 °C by a sol-gel method. The structure, morphology, and electrochemical performance of the as-prepared samples were characterized by means of X-ray diffraction, scanning electron microscopy, electrochemical impedance spectroscopy, and the galvanostatic discharge–charge techniques. It is found that the Cu-doped Li1.2V3O8 sample exhibits less capacity loss during repeated cycling than the undoped one. The Cu-doped Li1.2V3O8 sample demonstrates the first discharge capacity of 275.9 mAh/g in the range of 3.8–1.7 V at a current rate of 30 mA/g and remains at a stable discharge capacity of 264 mAh/g within 30 cycles. Furthermore, the possible role that copper plays in enhancing the cycleability of Li1.2V3O8 has also been elucidated.

The layered cathode materials of LiV3O8 were successfully prepared for the lithium rechargeable battery via a wet-chemistry synthesis method. The as-synthesized materials were characterized by XRD (powder X-ray diffraction), SEM (scanning electron microscope) and galvanostatic charge-discharge test. The results indicate that this soft-synthesis technique offers reduced calcinations temperature, preferred surface morphology and better electrochemical performance. Among the thus-prepared materials, the material obtained at 350 °C demonstrates the first discharge capacity as high as 308 mAh g-1 in the range of 4.0 ∼1.7 V at a current rate of 30 mA g-1 and remains at a stable discharge capacity of 250 mAh g-1 within 30 cycles.